As the conventional technology, a control apparatus for an internal combustion engine that has a configuration that performs a deterioration determination with respect to a catalyst while executing so-called “active air-fuel ratio control” is known, as disclosed, for example, in Patent Literature 1 (Japanese Patent Laid-Open No, 2010-159701). According to the conventional technology, the control apparatus measures an oxygen storage capacity (OSC) of a catalyst while causing the actual air-fuel ratio to track a target air-fuel ratio by changing the actual air-fuel ratio to a rich side and a lean side by active air-fuel ratio control. Further, the control apparatus is configured so as to correct a measurement value of the OSC based on a deviation between the actual air-fuel ratio and the target air-fuel ratio, and determine deterioration of the catalyst based on the OSC measurement value after the correction.
The applicants are aware of the following literature, which includes the above described literature, as literature related to the present invention.